This topic is covered extensively in Deva's book, and in JWG's first book on Pluto. Very simply, a planet conjunct the N.Node means that that archetype has already been embraced by the Soul just previous to the current life in order to evolve, and is meant to continue that evolution in this life via the planet conjunct the N.Node. With a planet on the S.Node it means on of three possible evolutionary/ karmic conditions. One is a total relieve of past life conditions that have not be resolved or avoided, two is a condition wherein that planet and S.Node have been highly developed to the point of constituting a natural resource that is being b brought forwards into the current life for the Souls own karmic and evolutionary reasons, and three is a combination of both one and two.